1. Field of the Invention:
The present invention relates to a mill roll stand of an unwinding apparatus for successively feeding a necessary amount of rolled sheet (raw paper sheet) while holding the roll at its axis in a corrugate machine, a rotary press and the like, and more particularly to an adjustable device for an arm shaft position of the mill roll stand.
2. Description of the Prior Art:
One example of the mill roll stand in the prior art is schematically shown in FIGS. 4 and 5. As shown in these figures, principal constituent elements of the mill roll stand are main body frames 17, a pair of arms (support arms) 1, an arm elevator 18, a horizontal arm mover 19 and rolling centers 14, and besides the mill roll stand comprises a manipulating unit, a control unit, drive units for the respective members and the like, which are omitted from illustration.
Explaining now the mill roll stand in the prior art in more detail, by way of example, in connection to a production line of a corrugated cardboard sheet, main body frames 17 are fixedly installed at predetermined positions on a floor of the same production line, and on these main body frames 17 are provided a pair of arms 1 in an opposed relation to each other, which arms hold the rolling centers 14 at their tip ends, and which arms are adapted to slide horizontally as driven by the horizontal arm mover 19 and to swing about an arm shaft 2 at their base ends as driven by the arm elevator 18. These arms are mounted two pairs as aligned back and forth in the direction of feeding the sheet.
The arms 1 are mounted on arm shafts 2 via sliding keys not shown, each of the arm shafts 2 has its opposite ends rotatably supported from left and right frames 7, 7 via bearings 3, 3, and the arm elevator 18 has such structure that the rolling centers 14 at the tip ends of the arms 1 can be elevated and lowered as swung up and down by swinging a lever 21 fixedly secured to the arm shaft 2 by means of a cylinder 22 connected to the other end of the lever 21.
Next, explanation will be made briefly with respect to loading of a rolled sheet (raw paper sheet) 16.
A rolled sheet 16 carried in from the outside by means of a roll conveyor 15 and placed at a predetermined position is loaded through the following procedure.
The rolling centers 14 held by the arms 1 are rotationally lowered by the cylinder 22 under the horizontally separated condition and stopped at the position aligning in height with the center of the rolled sheet 16.
In response to a next signal sent from the control unit not shown, the arms 1 would slide along the arm shaft 2 so as to approach to each other as driven by the arm horizontal mover 19, and the rolled sheet 16 has its center core pipe portion pinched by the rolling centers 14. Subsequently, the rolled sheet 16 is raised up to a predetermined height by the action of the cylinder 22, and thus setting of the mill roll stand has been completed.
On the other hand, on the other pair of arms 1 provided on the opposite side is also loaded a rolled sheet 16 through a similar procedure to that described above, and it is made to stand by as a spare rolled sheet so that as soon as the rolled sheet 16 being supplied has been used up the rolled sheet in a standby state may be spliced to the end of the consumed rolled sheet to continue the production in the subsequent stage. In this way, by alternately splicing the rolled sheets 16 loaded on the two sets of arms 1, respectively, as pinched thereby, it becomes possible to continuously produce a corrugated cardboard sheet. Exchange of rolled sheets as a result of order change or consumption of a rolled sheet can be carried out by proceeding the aforementioned procedure of loading.
However, in the mill roll stand in the prior art, as shown in FIGS. 4 and 5, the opposite ends of each arm shaft 2 are pivotably supported via bearings 3 at fixed positions on the side surfaces of the frames, hence the rolling centers 14 at the tip ends of the arm 1 which swings about the arm shaft 2 would pass along a circulararc-shaped locus, and therefore, the mill roll stand had a structural defect that during ascent and descent, a horizontal distance S of the rolling center 14 from the center of the machine would vary. Accordingly, the phenomena that the axis of the rolling center 14 would deviate greatly in the horizontal direction from the center of the rolled sheet 16 depending upon the diameter of the rolled sheet 16, may possibly happen.
In FIG. 4, distances represented by P.sub.1 and P.sub.2, respectively, are the possible deviations in the horizontal direction of the axis of the rolling centers 14, which would vary depending upon the diameter of the rolled sheet 16. By the way, with regard to the diameter of the rolled sheet 16, rolled sheets having various sizes between 330 mm and 1540 mm in diameter are used.
As described above, in the prior art since the arms swing up and down about the arm shaft having its opposite ends pivotably supported via the bearings fixedly mounted to the side surfaces of the left and right frames, the locus of the rolling center at the tip end of the arm would depict a circular arc.
Whereas, the center axis of the rolled sheet carried in from the outside by means of a roller conveyor is always positioned on the center vertical plane of the roller conveyor. Accordingly, between the axis of the rolling centers and the center axis of the rolled sheet is produced a deviation indicated by P.sub.1 or P.sub.2 in FIG. 4 depending upon the diameter of the rolled sheet.
Due to the above-described structural defects, in the prior art it would possibly happen that upon loading a rolled sheet, it is forcibly displaced in the direction of the horizontal deviation by making use of tapered surfaces of the rolling centers, and upon exchange of rolled sheets as a result of order change or the like, the rolled sheet is released from the rolling centers, then it is displaced to rest on the roller conveyor, and thereafter a new rolled sheet is loaded in the abovedescribed manner. However, such forcible operations would not only result in damage of the paper sheet and the core tube portion of the rolled sheet as well as faults of the machine, but also become a bar against automation, and furthermore they serve as a great cause for degrading safety of the work.